| Birmingham -- Nearly half of Americans breathe air which falls short of the federal government's standards for acceptable air quality. But what does polluted air mean for our health? Continuing our weeklong look at air quality in Birminghm, WBHM's Andrew Yeager spoke with Dr. Ed Postlethwait. He's chair of UAB's Department of Environmental Health Sciences and an EPA advisor. Postlethwait says besides making things worse for those who already have asthma or respiratory conditions, air pollution can negatively affect kids.